1. Field of the Invention
The present invention relates to a photo film cassette, and a method of attaching light-trapping fabric to the same. More particularly, the present invention relates to a photo film cassette of which light-trapping fabric allows passage of photo film with a relatively small torque for a spool, and at the same time has a high light-trapping capability, and a method of attaching such light-trapping fabric to the same cassette.
2. Description Related to the Prior Art
A photo film cassette has a cassette shell for containing photo film. A magazine has a body for containing photographic paper or other photosensitive material. Either of the photo film cassette or the magazine has a passage port or slot, on the inside of which there is attached a light-trapping fabric or ribbon, which is referred to as plush in the field of photosensitive material JP-Y (Japanese Utility Model Publication No.) 37-21388 discloses a woven structure of the light-trapping fabric including a woven base fabric and pile threads woven to protrude from the base fabric JP-Y (Japanese Utility Model Publication No.) 61-34526 discloses a knitted structure of the light-trapping fabric including a knitted base fabric and pile threads knitted to protrude from the base fabric.
To produce the pile-knitted fabric, a double raschel knitting machine is used. The knitting machine knits two fabrics at one time in a state where two base fabrics are interconnected by the pile threads. The pile threads are then cut in the central position, so as to obtain two products of the pile-knitted fabric which has a continuous belt-shape, and in which the pile threads being short protrude from one surface of the base fabric. JP-A (Japanese Patent Laid-open Publication No.) 7-301888, which is a commonly assigned Japanese patent application, discloses a method in which a plurality of the cassette shell, are arranged on one line, the light-trapping fabric being long is attached to the plural cassette bodies consecutively, before the light-trapping fabric is cut piece from piece to obtain a plurality of separated cassette bodies.
The light-trapping fabric after the center cutting has pile threads all of which are bent and inclined in one direction, so that the light-trapping fabric has a reduced thickness. A pressing roller is used for applying pressure, which presses the light-trapping fabric against each of two walls inside the photo film passage port of the cassette shell. In the application of the pressure, the cassette shell and the pressing roller are moved relative to one another in a direction opposite to the inclination of the pile threads, for the purpose of erecting the pile threads. However erection of the pile threads remarkably raises resistance to an operation of drawing the photosensitive material. It is likely that gaps, such as pinholes, are formed between the pile threads, and light-trapping capability for the photo film passage port is degraded.